1. Field of the Invention
This invention relates to a fluid cylinder incorporating a long stroke and which utilizes relatively high fluid pressure and low fluid volume to lift heavy loads through a substantial vertical distance. It is desirable to utilize relatively high pressure and low volume in order to lift heavy loads through a substantial vertical distance as opposed to utilizing lower pressure and a substantially greater volume of fluid under pressure.
However, the utilization of high pressure and relatively low volume to effect a substantial vertical lift by an extendable and retractable cylinder in the past has meant the use of a cylinder which is relatively small in diameter and thus not operative to withstand lateral forces, particularly when the cylinder approaches its fully extended position.
2. Description of Related Art
Various different forms of fluid cylinders including some of the basic structural and operational features of the instant invention are disclosed in U.S. Pat. Nos. 3,087,626, 4,337,845, 4,359,206, 4,479,633 and 4,867,416. However, these previously known cylinder constructions do not include the plurality of annular guides of the instant invention which are sequentially brought into operation subsequent to initial extension of the cylinder.